diff --git a/src/core/osmo_io.c b/src/core/osmo_io.c
index 90ea674..8cc6d37 100644
--- a/src/core/osmo_io.c
+++ b/src/core/osmo_io.c
@@ -533,6 +533,7 @@
 }
 
 /*! Set the size and headroom of the msgb allocated when receiving messages
+ *  \param[in] iofd the file descriptor
  *  \param[in] size the size of the msgb when receiving data
  *  \param[in] headroom the headroom of the msgb when receiving data
  */